Railway-brake.



PATENTED JULY 7, 1903.

P. HALLOT.

RAILWAY BRAKE.

APPLIOATION PILED JULY 18, 1901.

2 SHEETS-SHEET 1.

H0 MODEL.

. lizmziz Z02 IQEcLu/ZJYa/ZZOZ PATENTED JULY 7, 1903.

P. HALLOT. RAILWAY BRAKE.

APPLIGATION'IILED JULY 18, 1901.

2 SHEETSB HEET 2- N0 MODEL.

17101 71 i07 fau/ ZJZQ Z20 2 9 UNITED STATES Patented July 7, 1903.

PATENT OFFICE.

PAUL l-IALLOT, OF VINCEN'NES, FRANCE.

RAI LWAY-BRAKE.

SPECIFICATION forming part of Letters Patent No. 733,195, dated July '7,1903.

Application filed July 18, 1901. Serial No. 68,840. (No model.)

To aZZ whom it may concern:

Be it known that LPAUL HALLofnengineer, acitizen of France, residing at79 Rue de Fontenay, Vincennes, France, have invented certain newauduseful Improvements in Railway-Brakes, of which the following is aspecification.

This invention relates to an apparatus adapted for usein connection withair-brakes in which the brake-blocks are applied by a decrease of thepressure in the main pipe and the brake cylinder and which is furtheradapted to be located on each coach provided with a brake between themain pipe and the cylinder.

The object of this apparatus is to regulate the admission of the airinto the cylinder for each coach according to the place which the coachoccupies in the train and of subsequently allowing the air to escape atthe right moment and in the desired proportions.

The apparatus of this kind at present in use comprise a movable deviceor piece which is set in action automatically by the fall in pressureand the working of which varies, therefore, with the pressure at themoment and with the extent of the reduction in pressure. These apparatusare unable to work at all if a grain of sand should get between themovable valve and its seating, or if they become frozen, or from wear ofthe parts, 850.

In any case they only work at a considerable reduction in pressure,andthey cannot be adjusted or regulated.

In the annexed drawings, Figure 1 is asection taken through the axis ofthe apparatus. Fig. 2 is a plan of the upper part thereof. Fig. 8 showsin plan a detail of the apparatus. Fig. 4 shows an elevation of thepressureregulating mechanism communicating with the train-pipe, thebrake-cylinder, and the auxiliary air-reservoir.

The apparatus consists of a metal box or casing a, formed in two partsto facilitate its being put together. The upper part is provided withtwo unions, so that the apparatus may be interposed in the main pipe I),and it is closed by a screw-plug 0, through which passes a strong screwd, which is guided by the centering-ring 6. (Shown in plan in Fig. 3.)The spindle of the screw d is furnished near one end with a conical headf, and the other end terminates in a square portion g, which allows ofthe screw being turned by means of a hand-lever h. The thread of thescrew d and the angle of the valve-conef are so proportioned andadjusted that a rotation of three hundred and fifty degrees completelycloses the passage between the two portions of the box or casing 0t. Topartially close this passage to certain strictly fixed and invariabledegrees, according as the apparatus is located more or less closely tothe source of the pressure reduction, it is sufficient to place thehand-lever h in an intermediate position and to keep it there. For thispurpose said hand-lever can be moved over a plate i, Fig. 2, providedwith depressions or notches, into which a plug 7c, actuated by a springm,enters. A stop a prevents the hand-lever makinga complete revolution.

The lower part of the apparatus communicates, by means of the passage 0,with the cylinder in which the fall of pressure takes place and with theatmosphere through the valve 13 and the orifices g. In this lower partis a movable diiferential piston r, the cup-leathers of which face eachother, and the area of the two piston-heads is in proper ratio, whichdepends upon the type of brake. In the following description it isassumed that the ratio is equal to six. The larger head of thedifferential piston carries a slide-valve s for closing thecommunication between the passage 0 and the upper part of the apparatus.A spring 25 is inserted between the valve-conef and this larger head,the power of said spring being the greater the farther the screw dislowered. Furthermore, its initial tension may be adjusted at will bymeans of the nut Z. Another spring a is inserted between the smallerhead of the piston r and the valve 19 and tends to keep the said valveclosed. A 'third spring n tends constantly to raise the valve 19 with aforce which can be adjusted by turning the nut to. By means of thecranked lever 00 this valve 19 can be opened, and thereby bring about areduction of pressure in the cylinder by a simple pull on the rope y,the spring a serving to restore the lever ac to its normal position.This being so, we will now consider the apparatus in the position shownin Fig. 1. If the main pipe be charged, the difierential piston rdescends and allows the air to enter the lateral passage 0, thecylinder, and the space between the two heads ofthe piston1*,therebypressing outtheir cup-leathers. The air gains admission to thespace between the two heads of the piston 7' through the leather cap ofthe lower piston. At this moment an equal pressure of air exists on thefour faces of the two piston-heads, which are therefore in equilibrium,and the differential piston r rises under the preponderating action ofthe spring n, at the same time cutting off communication between themain conduit b and the passage 0. The sensitiveness of the piston-rod isdetermined by the friction of its leathers along the walls of thecylinder and also by the tension of the springs t ttl). The initialsensitiveness of the difierential piston r is, for example, set at threehundred grams. This sensitiveness will be diminished by the partialrotation of the hand-lever h, it being assumed, for example, that theposition of said lever h, Fig. 2, corresponds to an overcharge of thevalve of one hundred grams, the result being that the differentialpiston 7" will only commence to move under a variation in pressure offour hundred grams. It is assumed that the force for imparting amovement to the piston notwithstanding the friction corresponds to areduction of three hundred grams in the main pipe and that the force forimparting a movement to the piston, notwithstanding the tension of thesprings, is one hundred grams, so, therefore, is obtained the said fourhundred grams that are necessary to impart a movement to the piston. Aslong as pressure in the main pipe is greater than three thousandsix-hundred (four thousand minus four hundred) the piston r restsimmovable. Assuming that, as a rule, the pressure in the main conduit orpiping b is four thousand grams and that a slight reduction in pressuretakes place therein-two hundred grams, for examplenothing will takeplace in the apparatus, and any further reduction in pressure can evenbe made without any result so long asit does not exceed fourhundredgrams; but as soon as the pressure in the main conduit becomes reducedto three thousand six hundred grams the dilferential piston 0" willberaised by reason of the excess of pressure of four hundred grams on thelower face of this piston. The spring u will expand, and the valvep willopen under the action of the spring 1), which has become preponderant.The air in the cylinder will therefore escape rapidly into theatmosphere until the reduction of pressure under the smaller pistonheadbecomes equal tosix times four hundred grams, since the said piston-headis six times smaller than the larger one, and when the pressure in thecylinder has fallen to sixteen hundred grams the differential r (betweenthe pistons of which always exists the initial pressure of four thousandgrams) will no longer be influenced except by the action of the springs25, u, and 'u. If, for instance, a force of four hundred grams benecessary to reclose the valve 1), it is clear that the differentialpistonwill not descend, and this closurewill only be effected when thepressure in the cylinder has fallen to twelve hundred grams. Theapparatus will assume the position shown in Fig. 1, with the followingpressures: three thousand six hundred in the main conduit or pipingb,four thousand between the heads of the pistons 0', twelve hundred in thepassage 0 and the cylinder. This considerable fall in pressure in thecylinder resultsin avery great braking power, and this power is obtainedby a simple reducing in pressure of four hundred grams in the mainconduit or piping. To moderate this power in case the engineman deems ittoo considerable, it is only necessary to slightlyincrease the pressurein the main conduit 1), this increase of pressure causing thedifferential piston to fall and to open the port in the passage 0. Thebraking power can therefore be diminished gradually until completeremoval of the brakes, if necessary, while recharging simultaneously themain conduit.

The advantages of this system are obvious, as it allows of the brakingof a train under theoretical conditions, viz:

First. The quickest possible application of the maximum pressure uponthe brake-blocks.

Second. The gradual diminution of the pressure, so as to avoid theskidding of the wheels, which would take place by reason of thecoefficient of friction between the brakeblocks and the tire of thewheel increasing with the decrease in the rate of rotation of the wheel.The coefficient of friction between the brake-blocks and the tire of thewheel increases with the time of application; the longer the blocks areapplied the greater the coefficient. If, therefore, the pressure was notdecreased on the blocks, the wheels would rapidly be skidded.

Third. The very rapid removal of the brakes, so as to avoid rupture ofcouplings. In the system which has just been described the taking off ofthe brakes only requires the introduction of a very small quantity ofair into the main conduit, for even in extreme cases (emergencystoppages) the pressure to be reinstated in the conduit for taking olfthe brakes is at most four hundred grams. This apparatus renders itpossible by the simple setting of the hand-lever h at the desired placeto retard the action of the head brakes in order to obtainsimultaneousness of application of all the brakes of the train. Theposition of the valvef is set by means of the hand-lever 72-, asheretofore set forth. (See Fig. 2 of the drawings.) The operation of thepiston is as follows: hen the pressure in the main pipe is fourthousand, this pressure is the same in the whole apparatus, asheretofore set forth. )Vhen the pressure is, for example, three thousandeight hundred in the main pipe, the reduction of two hundred grams seeksto raise the piston 0 but this is not snfiicient to overcome thefriction of the leathers and the tension of the springs, as hereinbeforeset forth. The piston will only undergo motion when the reduction ofpressure attains three hundred grams. Then the pressure in the main pipefalls tothree thousand six hundred, the piston r rises, as heretoforeset forth. The pressure inthe main pipe is never allowedto fall belowthree thousand six hundred. NVhen it increases, the piston falls,uncovers the passage 0, and the air from the main or train pipes fillsthe brakecylinder until equilibrium is again attained. For the headcoaches the valve f almost completely closes the passage between the twoportions of the apparatus, at the same time overcharging thedifferential piston r and the valve p; but for the tail coaches saidpassage is fully open and the sensitiveness of the differential deviceis at the maximum. By all these means combined the braking of the tailcoaches is thus facilitated and that of the head coaches is retarded.

As seen, the screw-spindle d is rigid. It is adjusted at the time ofmaking up the train, according to its place therein, and from thatmoment it remains stationary whatever the pressure in the main conduitand the reduction in pressure caused therein. The initial sensitivenessof the differential piston 1' may be adjusted at will by the nuts to andZ, so as to effect the comparability of the apparatuses, without whichthe subsequent adjustment by setting the hand-lever It would bedeceptive. This setting has the efifect of causing the degree of thissensitiveness to vary, according to the place of the apparatus on thetrain.

In Fig. 4 is shown the pressure-regulatingvalve mechanism connected tothe train-pipe b and communicating with the auxiliary reservoir A andthe brake-cylinder B.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent, is-

1. In a fluid-pressure railway-brake, the combination with thetrain-pipe and the cylinder in which the lowering of pressure is to beefiected, of a regulating mechanism communicating with said pipe andadapted to retard the action of the head brakes relatively to that ofthe tail brakes and thus efiecting the simultaneous action of all thebrakes of the train, a screw-threaded valve-stem connected with andadapted to adjust said mechanism to obtain the aforesaid operation, anda lever for controlling the said stem.

2. In a fluid-pressure railway-brake, a pressure reducing mechanismcommunicating with the main pipe and with the cylinder in which thelowering of pressure is to be effected, said mechanism comprising in itsconstruction an adjustable means for cutting off communication betweenthe upper and lower portions of said pressure-reducing mechan ism, aslide-valve for cutting 0E communication between said mechanism and saidcylinder, a differential piston for operating said slide-valve, andmeans for cutting off communication between said mechanism and theatmosphere.

3. A pressure-regulating mechanism for railway-brakes comprising in itsconstruction,

operating the exhaust-valve, and means for adjusting the conical head.

5. In afluid-pressure railway-brake, a pressure-regulating mechanismcommunicating with the train-pipe and with the cylinder in which thelowering of pressure is to be efiected, said pressure-regulatingmechanism provided with a differential piston whose cupleathers faceeach other so as always to preserve between the two heads of the pistonthe maximum pressure for the purpose of effecting the braking, anadjustable valve-stem, an upper and lower spring for controlling thesensitiveness of the piston, and means for operating the said stem.

6. A pressure regulating mechanism for railway-brakes comprising in itsconstruction a casing, a conical head operating in the casing andadapted to regulate the supply of air from the train-pipe, meansconnected to said head for fixedly adjusting it, a slide-valve, a dilferential piston carrying the said valve, a spring interposed betweensaid means and valve, an exhaust-valve, a spring interposed between thepiston and said exhaust-valve, and means for operating theexhaust-valve.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

PAUL I'IALLOT.

Witnesses:

ALFRED FREY, EDWARD P. MAcLEAN.

TIC

